Systems for underwater sandblasting



R. F". FONTi SYSTEMS FOR UNDERWATER SANDBLASTING June 6, 1967 Filed Aug.20, 1964 INVENTOR ROCCO P. FONTI W amp "l-CLE ATTORNEY United StatesPatent 3,323,257 SYSTEMS FOR UNDERWATER SAN DBLASTING Rocco P, Fonti,Vernon Motel, 32 Vernon St., Plymouth, Mass. 02360 Filed Aug. 20, 1964,Ser. No. 390,883 1 Claim. (Cl. 51--8) This invention relates generallyto underwater sandblasting and more particularly is directed towards newand improved systems for the efiioient delivery of air and sand mixturesto sandblasting guns in underwater opera tions.

Sandblasting as a cleaning technique has been practiced for many yearsand has been found useful for the cleaning of castings and other metalwork in addition to abrading surfaces for useful as well as decorativepurposes. Sandblasting also has been widely used for the periodiccleaning of buildings, bridges, ships and similar structures.Heretofore, sandblasting has been used only for above waterapplications. However, in my Patent No. 3,256,642, dated June 21, 1966,there is disclosed an underwater sandblasting gun specifically designedand adapted for carrying out efficiently the cleaning of underwatersurfaces by sandblasting. The present invention concerns itself with theprovision of improved systems for supplying a flow of sand and airmixture in sufiicient volume, at the proper pressure and at the propervelocity for efficiently carrying out underwater sandblastingoperations.

Accordingly, it is an object of the present invention to provideimprovements in sandblasting systems having particular utility inunderwater sandblasting operations.

Another object of this invention is to provide sandblasting systemsadapted to deliver a flow of high-pressure high-velocity air and sand ona continuous basis to a gun located below the surface of the water.

More particularly, this invention features a system for use inunderwater sandblasting operations comprising a source of compressedair, a gun to be located below the surface of the water, a conduitconnecting the gun to the source of compressed air, a feeding systemconnecting the conduit to a supply of abrasive particulate material,means for producing a high-velocity mixture of air and sand within theconduit and means connecting the conduit to the supply system to improveevacuation of the supply system.

However, these and other features of the invention, along with furtherobjects and advantages thereof, will become more fully apparent from thefollowing detailed description of preferred embodiments of theinvention, with reference being made to the accompanying drawings, inwhich:

FIG, 1 is a view in side elevation partly in section of a system for usein underwater sandblasting made according to the invention, and

FIGS. 2, 3 and 4 are views similar to FIG. 1 but showing modificationsthereof.

Referring now to the drawings, the reference character generallyindicates a compressed air system comprising a motor 12, an aircompressor 14 and a charging tank 16. The tank 16 is connected by aconduit 18 to a dispensing tank 20 which, in turn, is connected by aconduit 22 to an underwater sandblasting nozzle 24 preferably of thesort shown in my Patent No. 3,256,642 dated June 21, 1966, located belowthe surface of the water and, in operation, is spaced from and directedat a surface 26 to be cleaned.

The dispensing tank 20 comprises a hopper 28 mounted on top of the tankdirectly above a vertically moveable filling valve 30. This fillingvalve 30 is controlled by means of an air line 32 connected to theconduit 18 and cleaning.

passing into the tank 20. It will be understood that the filling valve30 automatically closes when air passes through line 32 andautomatically opens when air is eX hausted through a three-way valve 34.The tank 20 is thus maintained under a pressure to balance with thepressure within a mixing chamber 36 located at the base of the tank 20and feeding into the conduit 22. With the pressures balanced between themixing chamber 36 and the interior of the tank 20 abrasive particulatematerial 38, such as sand or the like, will drop freely by gravitythrough the mixing chamber 36 into the conduit 22. A gate valve 40 maybe provided to control the flow of sand 38 through the mixing chamber.

In the operation of the system, it is necessary that the dischargepressure at the nozzle 24 be greater than the water pressure surroundingthe nozzle. It has been found that in depths down to 30 feet or so, airpressure of 80 p.s.i. or more is required for efiicient cleaning to takeplace. In depths down to about 100 feet a pressure of 100 to 175 p.s.i.is required to obtain effective sandblast In addition to sufiicient airpressure to overcome the water pressure, it is also necessary that therebe a relatively high volume output of air from the compressor and forgeneral underwater work a capacity of 125 cubic feet per minute isrequired. Various types of abrasive material may be used and, inpractice, sea sand or silica sand is preferred since they possessgreater hardness and are rougher grained than lake or river sand.Abrasives such as steel grit and shot may be employed but thesematerials are more expensive and the nature of the work does not permitconvenient recovery of the abrasive as may be done with open-airsandblasting.

Referring now more particularly to FIG. 2 of the drawings, there isillustrated a modification of the invention and in this embodiment anair compressor system 10 is connected by a conduit 42 to an eductor 44which takes suction on a pile 46 of abrasive material through a conduit48. The eductor 44 is connected by conduit 50 to a nozzle 52 forunderwater sandblasting.

In FIG. 3 there is illustrated another modification of the invention andin this embodiment an air compressor system 10 is connected to adispensing tank 54 of a construction similar to that of the tank 20 inFIG. 1 with the exception that a line 56 has been added to deliver a Howof pressurized air to the base of the hopper to facilitate clearing thesand through the filling valve. The dis charge from the dispensing tank54 is delivered to a conduit 58 into a venturi tube 60 which increasesthe velocity of the sand and air mixture and thereby provides animproved underwater cleaning. A conduit 62 connects the venturi 60 to anozzle 64.

Referring now more particularly to FIG. 4 of the drawings, there isillustrated a further modification of the invention and in thisembodiment a relatively high pressure water pump 66 taking suction on aline 68 delivers a flow of pressurized water through a conduit 70 into asand dispensing unit 72. This unit includes a hopper 74 having a flowcontrol valve 76 for delivering a flow of sand into an eductor 78. Theeductor 78 is operated by a flow of pressurized water introduced througha line 80 and discharging as a mixture of sand and water into a tank 82.Within the tank 82, the air and water mixture is delivered by a tube 84into a second eductor type mixing station 86 where it is combined with afiow of highpressure water fed through a tube 88 and the combineddischarges are fed into a single conduit 90 for delivery to a nozzle 92located under water.

The systems illustrated and described herein are particularly useful forunderwater sandblasting and are adapted to provide the continuous flowof high-pressure, high-volume and high-velocity output which is requiredfor efficient underwater sandblasting operations. The sys- :tems arerelatively simple and yet are well adapted for eflicient operationwithout clogging of the lines as occurs frequently with conventionalsystems.

While the invention has been described with particular reference to theillustrated embodiments, it will be understood that numerousmodifications thereto will appear to those skilled in the art.Accordingly, the above description and accompanying drawings should betaken as illustrative of the invention and not in a limiting sense.

Having thus described the invention, what I claim and desire to obtainby Letters Patent of the United States is:

A system for underwater sandblasting, comprising (a) conduit,

(b) a nozzle adapted for use underwater connected to one end of saidconduit,

() means connected to the opposite end of said conduit for delivering tosaid conduit a flow of fluid at a sufficient pressure and velocity andin suflicient volume to discharge through said nozzle when said nozzleis disposed under water,

(d) means for storing a quantity of particulate abrasive material inproximity to said conduit,

(e) feeding means responsive to the flow of said fluid for transferringregulated amounts of said abrasive material from said storing means intosaid conduit,

(f) said feeding means including a hopper adapted to dispense a flow ofabrasive material, a pressure tank disposed below said hopper to receivesaid material and connected to said pressurized fluid, a fluid pressureresponsive valve mounted in said tank for controlling the flow of saidabrasive material into said tank and a mixing chamber connecting saidtank to said conduit wherein said abrasive material is mixed with saidfluid, and,

(g) venturi means connected to said conduit means between said nozzleand said feeding means for increasing the velocity of said fluid andabrasive material.

References Cited UNITED STATES PATENTS 999,485 8/1911 Carolin 5181,706,737 3/1929 Moore 5112 1,940,539 12/1933 Fritsche 5.18 2,200,587 5/1940 Tirrell 518 2,388,818 11/1945 Bick 518 2,455,514 12/1948 Mead 5182,613,482 10/1952 Hamacher 51-8 3,212,217 10/1965 Furgason 518 3,256,6426/1966 Fonti 5111 LESTER M. SWINGLE, Primary Examiner.

